A variety of resins having different applications can be prepared from particles of vinylaromatic copolymers of the gel or macroporous type. These include anion exchange resins of differing basicity prepared by chlorination and/or chloromethylation of the copolymers followed by amination, and cation exchange resins prepared by sulfonation of the copolymers using agents such as sulfuric acid and sulfuric anhydride. Also included are ionic and non-ionic decolorizing adsorbent resins.
For various applications of these resins, such as the separation of uranium from leach liquors or the regeneration of resins used in water treatment, it is advantageous to have resins having a density higher than that of commercially available resins, while retaining a good exchange capacity. In French Pat. No. 2,362,886 it is proposed to prepare high density resins of the ionic type by bromination of certain aromatic polymers.